Re: statfs() / statvfs() syscall ballsup...

[Trond Myklebust <trond.myklebust@fys.uio.no>]

>>>>> " " == Linus Torvalds <torvalds@osdl.org> writes:

     > (As to the read-ahead issue: there's nothing saying that you
     > can't wait for the pages if they aren't up-to-date, and really
     > synchronize with read-ahead. But that will require filesystem
     > help, if only to be able to recognize that there is active IO
     > going on. So NFS would have to keep track of a "read list" the
     > same way it does for writeback pages).

Well... I was thinking more in terms of a rw_semaphore to lock out new
calls to nfs_file_(read|write|sendfile) in combination with a call to
invalidate_inode_pages2().

Such a mechanism can also be used in schemes to improve on the generic
data/attribute cache consistency in order to reduce the number of
bogus cache invalidations due to RPC ordering races. Those can tend to
be expensive...

Note: Anybody using mmap() in combination with file locking will
however continue to enjoy the privilege of being able to screw up...

Cheers,
  Trond